Leslie Dewan, 27

With fellow MIT Phd candidate Mark Massie, 26, Dewan is working to develop a new nuclear reactor design. The Waste Annihilating Molten Salt Reactor (WAMSR) will utilize liquid fuel consisting mainly of the "spent" fuel rods from the nation's fleet of Light Water Reactors, which Dewan says still contain enough energy to power the entire U.S. for 70 years.